I think there are different reasons:

- Mandatory military service makes people know how to use guns

- People have mandatory health insurance and social security, means there is no need to shoot people for money

- Less racist police, means minorities dont solve problems by themselves with violence

- high minimum wage, so nobody has to starve

- Gun owners do not use guns to defend against burglars, so burglars also dont have to use guns

- Proper handling of drug addiction (including addicts)

- better mental health because of mandatory holidays, parental leaves, and a lot of chocolate

- Prostitution is legal, so no pimping